The present invention relates to an automatic transmission.
Japanese Patent Application Publication No. JP-A-2005-61436 (pp. 12 and 13, FIG. 1), discloses an automatic transmission which has an input shaft, a multiple planetary gear set for acceleration/deceleration, a multiple planetary gear set for shifting, an output shaft, first to fifth clutches, and first and second brakes. The automatic transmission shifts a rotation of the input shaft with twelve forward speeds and three reverse speeds to transfer the rotation to the output shaft.
The multiple planetary gear set for acceleration/deceleration is structured having a common carrier rotatably supporting a small-diameter pinion and a large-diameter pinion which are formed integrally on the same axis, a first sun gear meshing with the small-diameter pinion, a second sun gear meshing with the large-diameter pinion, and a common ring gear meshing with the large-diameter pinion. The multiple planetary gear set for shifting is structured having a common carrier rotatably supporting a long pinion and a pinion that mesh with each other, a third sun gear meshing with the long pinion, a fourth sun gear meshing with the pinion, and a common ring gear meshing with the long pinion.
The second sun gear of the multiple planetary gear set for acceleration/deceleration is fixed, and the common carrier is coupled directly to the input shaft. The third sun gear of the multiple planetary gear set for shifting can be coupled to the first sun gear of the multiple planetary gear set for acceleration/deceleration via the third and fifth clutches, and can be fixed via the first brake. The fourth sun gear can be coupled to the first sun gear of the multiple planetary gear set for acceleration/deceleration via the first and fifth clutches, and can be coupled to the common ring gear via the first and fourth clutches. The common carrier of the multiple planetary gear set for shifting can be coupled to the input shaft via the second clutch, and can be fixed via the second brake. The common ring gear of the multiple planetary gear set for shifting is coupled directly to the output shaft.